It really depends on the magazine... and the book. Today I have magazines that I've collected since I was a teen... over 30 years of magazines that I still go back and reference for one thing or another. Whereas, in those 30 years, I've disposed of quite a few books.

I'm not going to try to predict the display technologies of the future. I will say that the most popular displays will be those that can handle B/W and color.

And there's no reason ads can't find their way into ebook delivery. They get into every other type of medium, and after an initial "I hate ads!" response from consumers, they duly get used to them, no matter how invasive they are. Advertisers have our number.

As for cloud-based services: There will always be someone who will offer an app that will pull your content off the cloud and allow you to store it yourself. The only thing preventing everyone from using that app will be laziness.